This invention relates generally to umbrellas, and more particularly, is directed to an umbrella that is resistant to inversion from the wind.
Quite frequently, a wind will catch an umbrella user unaware and exert a force against the inner surface of the canopy which will cause the canopy to invert from its normal operable position to an upwardly convex or bowed position.
Accordingly, specially designed umbrellas for rainy, windy weather, have been proposed, as described, for example, in U.S. Pat. No. 3,032,047 to Wendorf. This patent discloses a storm umbrella with a canopy draped over the ribs and secured thereto and in which the canopy has a plurality of holes circumferentially arranged near the center thereof. A circular piece of fabric is disposed over the holes and is secured at spaced points to the ribs by stitching or the like. Accordingly, free passages for air exist underneath the unattached portions of the circular piece of fabric and through the holes in the fabric cover. However, this umbrella provides little resistance to inversion due to high winds. This is because the openings are provided at a radially inward position which is extremely close to the hub and therefore have a very small diameter. Furthermore, because the circular piece of fabric is stitched to the ribs, there is little flexibility thereof. Accordingly, the space between the canopy and the circular piece of fabric is very small and therefore provides a high resistance to wind exiting through the holes in the canopy. Still further, in extremely adverse weather conditions, a heavy rain may enter the space between the canopy and the circular piece of fabric and fall through the holes in the canopy onto the user. This is particularly the case where only a small circular piece of fabric is used to cover the canopy, as in U.S. Pat. No. 3,032,047. An umbrella which is similar in construction and therefore suffers from the same disadvantages is disclosed in U.S. Pat. No. 1,031,974 to Thomas.
A windproof umbrella is disclosed in U.S. Pat. No. 3,456,661 to Farley in which the main umbrella cover has a relatively large circular central opening concentric with the center pole and which may extend radially outwardly for a distance up to one-half of the dimensions of the radially oriented ribs. An upper umbrella covering comprised of a plurality of tapered, generally triangular gores 12 is positioned above the main umbrella covering and extends to a distance beyond the perimeter of the central hole thereof. Each gore is secured at its radial edges to the umbrella along the lines defined by two radially oriented ribs and has dimensions wider than the width between those ribs, the gores being secured either to the ribs or to the material of the main umbrella covering itself. Accordingly, a plurality of generally arcuate flying vents are formed which are adapted to fill with air rising from below through the central hole and expel the air horizontally when the radial ribs are rigidly held in position. When the air pressure above and below the umbrella is equalized, the flying vents are adapted to collapse and form a loose covering over the central hole of the main umbrella covering to thereby shed rain in the normal fashion. It is clear from this patent that, when the arcuate flying vents are filled with air, such as shown in the figures of the patent, inversion of the umbrella is prevented. However, this patent provides the disadvantage that rain can easily enter the central opening of the main umbrella covering when the flying vents are filled with air, and to this end, the windproof umbrella of this patent would not be practical.
Umbrellas of a similar nature are disclosed in French Patent Nos. 817,056 and 1,284,022. In addition to the remarks above, with these patents, the circular piece of fabric appears to be held in an arcuate position by rigid piping or the like.
U.S. Pat. No. 3,960,162 to Noel discloses a vented umbrella. With this umbrella, openings are formed in the covering material over each rib and a rigid pivoted vent is assembled with the struts over each opening. Accordingly, during heavy winds, a large wind pressure at the underside of the umbrella will pivotally raise the vents so as to exit through the openings. However, when the vents are pivotally opened, rain can enter therethrough.
U.S. Pat. No. 3,863,660 to Glaeser discloses a method and apparatus for controlling sunlight transmission and includes an umbrella having a lower canopy with a plurality of holes throughout the canopy. In such case, the openings permit some of the sunlight to pass therebetween to the user. If it is desired that no sunlight enter the umbrella, an outer canopy or covering may be employed in covering relation to the openings. In such case, the outer canopy has a plurality of holes around the peripheral edge thereof through which the free ends or tips of the ribs can extend for holding the outer canopy in place. However, the umbrella of this patent is not intended to be used against heavy winds and is merely used as a parasol to prevent sunlight from entering. In any event, the dimensions of the outer covering are identical to those of the main canopy so that, even if such umbrella was used in rainy, windy weather, it would be difficult to exhaust the air from the space between the inner and outer canopies.
Umbrellas in which two canopies, or a detachable canopy, has been used for aesthetic purposes or the like, are described in U.S. Pat. Nos. 1,145,768; 1,785,561; 2,746,469; and 3,557,809.